Jon Carson, executive director of Organizing for Action, told the Los Angeles Times / Tribune Washington Bureau on Thursday that the group will train its resources against the 45 senators who opposed the legislation, including Democrats Max Baucus of Montana, Mark Begich of Alaska, Heidi Heitkamp of North Dakota and Mark Pryor of Arkansas.

“What is happening right now is the reason that OFA needs to be here: to harness the energy and determination of people,” Carson said. “I think everyone would agree that the American people are on our side on this…. We need to show that the 90% on our side have staying power.”

“This is one of those moments where we have to prove that in the face of a setback we’re not backing down,” he added. “That’s the calculation that some senators were mistaken on…. The consequences they’re going to have to face are a bunch of angry constituents who are going to keep the issue alive.”

Carson said Organizing for Action will also demonstrate support for those who backed the measure, including the Republican co-sponsor, Patrick J. Toomey of Pennsylvania.

“Our volunteers are ready to show Pat Toomey how much they appreciate his leadership,” he said.

The group plans to launch sustained campaigns in which constituents will call and tweet lawmakers, write letters to the editor and hold local events spotlighting their support for gun control. Its next major effort comes Saturday, when supporters are organizing rallies and other events in the states of key senators.

Calls and Tweets, letters to the editor, local rallies with mid-level attendance… eh, most incumbent senators don’t fear those actions, unless they come in overwhelming numbers. One of the big questions is just how many Organizing for Action members reside in Montana, Alaska, and Arkansas.

OpenSecrets.org compiled a sortable, downloadable list of the 1,428 donors who gave more than $250. They list four donors in Alaska, who contributed $1,375; four donors in Arkansas, who contributed $51,500; and three donors in Montana, who contributed $1,250. In Pennsylvania, the group lists 34 donors who contributed $12,888. As you might expect, those are small fractions compared to states like California, New York, Illinois, Massachusetts and Maryland.

As I wrote this morning, the rhetoric of the president and his supporters would suggest that the defeat of Baucus, Begich, and Pryor is a priority. But the real question will be whether any of their fury over yesterday’s vote translates into support for a pro-gun-control primary challenger. The filing deadline for a party candidate in Montana and Arkansas is March 2014; for Alaska the deadline is June 2014.